A 6.2-kg box is being lifted by meansof a light rope that is threaded through a

Question

A 6.2-kg box is being lifted by meansof a light rope that is threaded through a single, light,frictionless pulley that is attached to the ceiling. (a) If the box is being lifted at aconstant speed of 2.0 m/s, what is the power delivered bythe person pulling on the rope?
1___kW

(b) If the box is lifted, at constant acceleration, fromrest on the floor to a height of 1.5 mabove the floor in 0.42 s, what average power is delivered by theperson pulling on the rope?
2___kW (a) If the box is being lifted at aconstant speed of 2.0 m/s, what is the power delivered bythe person pulling on the rope?
1___kW

(b) If the box is lifted, at constant acceleration, fromrest on the floor to a height of 1.5 mabove the floor in 0.42 s, what average power is delivered by theperson pulling on the rope?
2___kW

Explanation / Answer

a) in one second, work done = 8.5*2*9.8 = 166.6 J power = 166.6 J/ 1sec = 166.6 w b) work = 8.5*1.5*9.8 = 124.95 J avg. power = 124.95/.42 = 297.5 w

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